• 분석과학
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• 제19권3호
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• pp.194-202
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• 2006

중국산 천연물질인 서장채국화, 홍경천 및 장청과에서 미백성분을 추출 및 정제하였다. 잘게 분쇄한 서장채국화와 장청과 잎을 각각 물과 에틸 에테르로 추출하고 제조용 크로마토그래피 GS310 컬럼($21.5{\times}500mm$ i.d., $10-15{\mu}m$)으로 네 개 혹은 세 개의 부분으로 획득한 후 농축하였다. 잘게 분쇄한 홍경천은 메탄올로 추출하고 분석용 $C_{18}$ 컬럼 ($3.9{\times}300mm$ i.d., $15{\mu}m$)으로 2개의 부분으로 획득한 후 농축하였다. 미백효과는 in-vitro 멜라닌 생성효과로 측정하였다. 이때 사용한 멜라닌-a와 B16 셀의 농도는 $10{\mu}g/ml$이다. $200{\mu}g/ml$의 농도에서 서장채국화의 에틸 아세테이트층은 92%의 멜라닌 억제효과를 보이며, 홍경천은 60%의 멜라닌 억제효과를 보였다. 이것은 모두 알부틴의 미백효과(45.6%)보다 우수하였다. $100{\mu}g/ml$의 농도에서 장청과는 90%이상의 멜라닌 억제효과를 나타냈지만 B16흑색종 셀에 대하여 독성을 보였다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1483-1490
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• 2011

The protection effect of a $ZrO_2$ coating layer on a $LiCoO_2$ thin film was characterized. A wide and smooth $LiCoO_2$ thin film offers sufficient opportunity for careful observation of the reaction at the interface between cathode (coated and uncoated) and electrolyte. The formation of a $ZrO_2$ coating on a $LiCoO_2$ thin film was confirmed by secondary ion mass spectrometry. Scanning electron and atomic force microscopy were used to characterize the surface morphologies of coated and uncoated films before and after cycling. A $ZrO_2$-coated $LiCoO_2$ film showed a higher discharge capacity and rate capability than an uncoated film. This may be associated with a surface protection effect of the coating. The surface of a pristine film was damaged during cycling, whereas the coated film maintained a relatively clear surface under the same measurement conditions. This result clearly demonstrates the protection effect of a $ZrO_2$ coating on a $LiCoO_2$ thin film.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.40-49
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• 2001

We have developed a repeatable process of forming uniform, small-size and high-density self-assembled Si nano-crystals. The Si nano-crystals were fabricated in a conventional LPCVD (low pressure chemical vapor deposition) reactor at $620^{\circ}c$ for 15 sec. The nano-crystals were spherical shaped with about 4.5 nm in diameter and density of $5{\times}l0^{11}/$\textrm{cm}^2$. More uniform dots were fabricated on nitride film than on oxide film. To take advantage of the above-mentioned characteristics of nitride film while keeping the high interface quality between the tunneling dielectrics and the Si substrate, nitride-oxide tunneling dielectrics is proposed in n-channel device. For the first time, the single electron effect at room temperature, which shows a saturation of threshold voltage in a range of gate voltages with a periodicity of ${\Delta}Ｖ_{GS}\;{\approx}\;1.7{\;}V$, corresponding to single and multiple electron storage is reported. The feasibility of p-channel nano-crystal memory with thin oxide in direct tunneling regime is demonstrated. The programming mechanisms of p-channel nano-crystal memory were investigated by charge separation technique. For small gate programming voltage, hole tunneling component from inversion layer is dominant. However, valence band electron tunneling component from the valence band in the nano-crystal becomes dominant for large gate voltage. Finally, the comparison of retention between programmed holes and electrons shows that holes have longer retention time.

• 한국전기전자재료학회논문지
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• 제15권7호
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• pp.583-590
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• 2002

In this paper, a new Silicon on Insulator (SOI)-based photodetector was proposed, and its basic operation principle was explained. Fabrication steps of the detector are compatible with those of conventional SOI CMOS technology. With the proposed structure, RGB (Read, Green, Blue) which are three primary colors of light can be realized without using any organic color filters. It was shown that the characteristics of the SOI-based detector are better than those of bulk-based detector. To see the response characteristics to the green (G) among RGB, SOI and bulk NMOSFETS were fabricated using $1.5\mu m$ CMOS technology and characterized. We obtained optimum optical response characteristics at $V_{GS}=0.35 V$ in NMOSFET with threshold voltage of 0.72 V. Drain bias should be less than about 1.5 V to avoid any problem from floating body effect, since the body of the SOI NMOSFET was floated. The SOI and the bulk NMOSFETS shown maximum drain currents at the wavelengths of incident light around 550 nm and 750 nm, respectively. Therefore the SOI detector is more suitable for the G color detector.

• Geomechanics and Engineering
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• 제8권5호
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• pp.675-685
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• 2015

Weathering is the breaking/cutting down process of rocks due to physical and chemical processes in natural as well as artificial environment including $CO_2$ injection for storage in the sediment, or natural resource recovery process. This study suggests an alternative method to estimate the degree of weathering for granites. A series of laboratory and field experiments are performed to measure electrical resistivities on various rock samples experienced different degrees of weathering and their residual soils under different saturation conditions. It is found that the normalized electrical resistivity increases with a decrease in water absorption and the saturation. Simple boundaries are suggested to identify the weathering degree of granites, based on limited data. Field test results for three sites confirm that the suggested method could be estimated well the degree of weathering of granites compared with the other methods suggested previously. Although further research is required, this study suggests that an electrical resistivity could be an effective approach to estimate the degree of weathering of granites compared with the other methods suggested previously.

• Asian-Australasian Journal of Animal Sciences
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• 제12권7호
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• pp.1063-1069
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• 1999

Wheat straw samples (3-4 cm) were sprayed with solutions of urea (U) alone or with a dry addition of garden soil (GS), midden soil (MS), soya bean meal (SM) or jack bean meal (JM) as crude urease sources and with a pure urease (UR) enzyme. Each of the urease sources was included at two levels: 30 and 60 g/kg except pure urease, which was added at a level of 2.5 & 5.0 g/kg treated straw dry matter. Untreated straw without urease source was used as a control. After treatment, samples were sealed in polythene bags and stored for 2, 7, 14, 21 and 35 days at $19{^{\circ}C}$. The urease sources, their levels and treatment time produced significant effects on ammonia production (p<0.01). The addition of urease offered more flexibility in hydrolyzing urea in the shortest possible time. Incorporation of soya bean and jack bean meal was effective in reducing the modified acid detergent fiber (MADF) content of straw and the same time increasing organic matter (OM) digestibility. Overall effect, addition of soya bean to urea at a ratio of 1:1 appeared to be the most satisfactory urease source for the treatment of urea and wheat straw.

• 설비공학논문집
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• 제26권5호
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• pp.231-239
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• 2014

This paper represents a method of existing building energy simulation using energy audit data. Energy audit must be carried out for reasonable analysis, because characteristics of existing buildings such as efficiency of fan, pump, flow rate, pressure, COP and operating schedule could be changed during the building operation. These building characteristics should be measured to estimate actual energy consumption of the existing building. In this study, we conducted energy audit and calculated energy savings for a 7-stories building as a case-study. The energy audit data were used to calibrate the building model of EnergyPlus simulation. Baseline model validated according to M&V guideline index. As a result, building characteristics are significant parameters making a big impact on energy savings in existing buildings.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.154-154
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• 2013

In this work, we investigated the characteristics and the effects of light on the negative gate bias stress stability (NBS) in high mobility polycrystalline IGO TFTs. IGO TFT showed a high drain current on/off ratio of ${\sim}10^9$, a field-effect mobility of $114cm^2/Vs$, a threshold voltage of -4V, and a subthresholdslpe(SS) of 0.28V/decade from log($I_{DS}$) vs $V_{GS}$. IGO TFTs showed large negative $V_{TH}$ shift(17V) at light power of $5mW/cm^2$ with negative gate bias stress of -10V for 10000seconds, at a fixed drain voltage ($V_{DS}$) of 0.5V.

• 대한안전경영과학회지
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• 제8권5호
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• pp.99-117
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• 2006

Consumers keep demanding for diversified high quality products, valuable services and safety. With this in mind, Distribution Industry is being updated rapidly to accomodate this demand. Meanwhile, Distribution Information Technology of agricultural products has been in slow progress with little in-depth studies. In this study, it has been analyzed the usage of Bar code which is the key element for agricultural Distribution Information Technology. The analysis was conducted through a survey utilizing questionnaire covering 5 Hypermarkets(Super-centers) including big 3 companies. Also, Japanese market trends have been studied to visit a Japan Government Organization concerned, GS1 Japan, an Agricultural Cooperative, an Agricultural Wholesale Market, and a Retail Company. If we could use KAN code for all agricultural products, we could collect and analyze the information of price and trade quantity of them. It opens a new era to understand the agricultural products supply and demand easily. This will certainly make a great contribution to the evolution of agricultural products distribution. From this research, it is suggested that collective efforts by suppliers, wholesalers, retailers and Government Officers are needed to make large scale mutual marketing Organizations, which specialize in sending out agricultural products. The Organization is recommended to standardize and pack every final agricultural products, to promote the use of KAN code.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.685-695
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• 2020

The connection performance between cross-laminated timber (CLT) walls and support has the greatest effect on the horizontal shear strength. In this study, the horizontal shear performance of CLT walls with reinforced connection systems was evaluated. The reinforcements of metal bracket connections in the CLT connection system was made by attaching glass fiber-based reinforcement to the connection zone of a CLT core lamina. Three types of glass fiber-based reinforcement were used: glass fiber sheet (GS), glass fiber cloth (GT) and fiber cloth plastic (GTS). The horizontal shear strength of the fabricated wall specimens was compared and evaluated through monotonic and cyclic tests. The test results showed that the resistance performance of the reinforced CLT walls to a horizontal load based on a monotonic test did not improve significantly. The residual and yield strengths under the cyclic loading test were 38 and 18% higher, respectively, while the ductility ratio was 38% higher than that of the unreinforced CLT wall. The glass fiber-based reinforcement of the CLT connection showed the possibility of improving the horizontal shear strength performance under a cyclic load, and presented the research direction for the application of real-scale CLT walls.